The photodynamic effect of chlorpromazine, promazine, and hematoporphyrin on lens protein.

Calf lens protein was irradiated with near ultraviolet (UV) light in the presence of the drugs chlorpromazine, promazine, and hematoporphyrin. It then was analyzed by SDS-polyacrylamide gel electrophoresis and amino acid analysis. Marked increases in protein photopolymerization (other than S-S bond formation) and histidine destruction were noted in the presence of these drugs. In all cases, these effects were reduced in the presence of a singlet oxygen quencher, thus suggesting that these photodynamic effects are due, at least in part, to a Type II mechanism.